FIG. 4 is a configuration explanatory view showing an example of a battery holder which has been conventionally used, in which the battery holder has a leaf spring-type electrode structure. In FIG. 4, a base plate 1 is formed in a rectangular shape having a long side with a length nearly equal to that of a battery BAT to be held thereon, and a positive electrode contact portion 2 made of a leaf spring is fixed on one end thereof in a longitudinal axial direction and a negative electrode contact portion 3 made of a leaf spring is fixed on the other end to oppose the positive electrode contact portion 2. Also, on both sides of the base plate 1, holding pieces 4 and 5 made of a leaf spring for holding the battery BAT to be attached thereon are fixed to oppose each other.
The positive electrode contact portion 2 and the negative electrode contact portion 3 have one end bent in an L-shape so that a bent side thereof is fixed on the base plate 1. The other end are bent in a mountain shape to serve as a contact portion, which can be pressed against and come in stable contact with each electrode of the battery BAT to be held thereon by an elastic force of the leaf springs.
Because the distal ends of the positive electrode contact portion 2 and the negative electrode contact portion 3 are bent in such a mountain shape, a distance therebetween is slightly wider than an axial length of the battery BAT to be fixed and held on the base plate 1, thereby allow the battery BAT to be easily inserted therebetween. Meanwhile, the positive electrode contact portion 2 and the negative electrode contact portion 3 are electrically insulated from each other via the base plate 1.
The holding pieces 4 and 5 are also made of a leaf spring, and middle parts thereof are fixed on the base plate 1 to be perpendicular to a longitudinal axial direction of the base plate 1. Both ends of the holding pieces 4 and 5 are bent in a substantially L-shape in the same direction to be pressed against side surfaces of the battery BAT to be attached by an elastic force of the leaf springs, and also are formed in a circular arc shape to sandwich the battery BAT on opposing sides thereof in a substantially close contact state. Also, distal end portions of the holding pieces 4 and 5 are bent outward away from each other to allow the battery BAT to be easily attached and detached.
FIG. 5 is a configuration explanatory view showing another example of a battery holder which has been conventionally used, in which the battery holder has a coil spring-type electrode structure. In FIG. 5, a case 6 is provided with partition walls 6a and 6b to define two battery housing portions 6c and 6d, thereby allowing two batteries BATs to be mounted therein. On a side of each of the battery housing portions 6c and 6d which opposes the partition walls 6a and 6b, hold portions 6e and 6f of a circular arc-shaped cross section are formed to hold the respective batteries BATs received therein by partially coming in close contact with a side surface thereof.
A positive electrode contact portion 7 made of a coil spring is fixed on one of wall surfaces of the battery housing portion 6c opposing each other along an axial direction thereof, and a negative electrode contact portion 8 made of a coil spring is fixed on the other wall surface. Similarly, a positive electrode contact portion 9 made of a coil spring is fixed on one of wall surfaces of the battery housing portion 6d opposing each other along an axial direction thereof, and a negative electrode contact portion 10 made of a coil spring is fixed on the other wall surface.
Meanwhile, the electrode contact portions 7 to 10 are insulated against the case 6. Also, the negative electrode contact portion 7 and the positive electrode contact portion 10 are electrically connected to each other so that two batteries BATs mounted in the battery housing portions 6c and 6d are connected in series to each other.
In the configuration of FIG. 5, for example, when the battery BAT is mounted and housed in the battery housing portion 6c, the battery BAT is tilted so that any one of contact coils 7 and 8 is pressed by one end of the battery BAT, and then is pushed therein until the other end of the battery BAT comes in stable contact with the other contact coil.
FIG. 6 is a configuration explanatory view of a battery holder as described in Patent Document 1. In FIG. 6, a positive electrode contact portion 21 is made of a leaf spring and a negative electrode contact portion 22 is made of a coil spring.